This invention relates to lighting and, more particularly, to light emitting diode (LED) illumination.
Over the years various types of illuminating assemblies and devices have been developed for indoor and/or outdoor illumination, such as torches, oil lamps, gas lamps, lanterns, incandescent bulbs, neon signs, fluorescent bulbs, halogen lights, and light emitting diodes. These conventional prior art illuminating assemblies and devices have met with varying degrees of success.
Incandescent light bulbs create light by conducting electricity through a thin filament, such as a tungsten filament, to heat the filament to a very high temperature so that it glows and produces visible light. Incandescent light bulbs emit a yellow or white color. Incandescent light bulbs, however, are very inefficient, as over 98% of its energy input is emitted and generated as heat. A standard 100 watt light bulb emits about 1700 lumens, or about 17 lumens per watt. Incandescent lamps are relatively inexpensive and have a typical lifespan of about 1,000 hours.
Fluorescent lamps (light bulbs) conduct electricity through mercury vapor, which produces ultraviolet (UV) light. The ultraviolet light is then absorbed by a phosphor coating inside the lamp, causing it to glow, or fluoresce. While the heat generated by fluorescent lamps is much less than its incandescent counterpart, energy is still lost in generating the UV light and converting UV light into visible light. If the lamp breaks, exposure to mercury can occur. Linear fluorescent lamps are often five to six times the cost of incandescent bulbs but have life spans around 10,000 and 20,000 hours. Lifetime varies from 1,200 hours to 20,000 hours for compact fluorescent lamps. Some fluorescent lights flicker and the quality of the fluorescent light tends to be a harsh white due to the lack of a broad band of frequencies. Most fluorescent lights are not compatible with dimmers.
Light emitting diode (LED) lighting is particularly useful. Light emitting diodes (LEDs) offer many advantages over incandescent light sources, including: lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and excellent durability and reliability. LEDs emit more light per watt than incandescent light bulbs. LEDs can be tiny and easily placed on printed circuit boards. LEDs activate and turn on very quickly and can be readily dimmed LEDs emit a cool light with very little infrared light. LEDs come in multiple colors which are produced without the need for filters. LEDs of different colors can be mixed to produce white light. Other advantages of LEDs include: high efficiency; low energy consumption; higher outputs at higher drive currents; shock resistant with no filament, glass or tube to break, contain no toxic substances, hazardous mercury or halogen gases.
The operational life of some white LED lamps is 100,000 hours and 11 years of continuous operation. The long operational life of an LED lamp is much longer than the average life of an incandescent bulb, which is approximately 5000 hours. If the lighting device needs to be embedded into a very inaccessible place, using LEDs would minimize the need for regular bulb replacement. With incandescent bulbs, the cost of replacement bulbs and the labor expense and time needed to replace them can be significant especially where there are a large number of incandescent bulbs. For office buildings and high rise buildings, maintenance costs to replace bulbs can be expensive and can be substantially decreased with LED lighting.
An important advantage of LED lighting is reduced power consumption. An LED circuit will approach 80% efficiency, which means 80% of the electrical energy is converted to light energy; the remaining 20% is lost as heat energy. Incandescent bulbs, however, operate at about 20% efficiency with 80% of the electrical energy is lost as heat. Repair and replacement savings can be significant, as most incandescent light bulbs burn out within a year and require replacements whereas LED light bulbs can be used easily for a decade without burning out.
LED light (lighting) bars are considered to be much better than incandescent lights. Incandescent light bulbs do not last for a long time and the filament burns out. A LED light bar consumes less energy and has a longer life. LED light output is much brighter than that of an incandescent light bulb.
An assortment of colors and flash patterns are available with LED light bars for emergency vehicles such as police cars, fire trucks and ambulances. Emergency vehicles such as ambulances and police cars prefer mounting a LED light bar on the top for easy recognition and visibility. LED light bars can be used on the interior as well as on the exterior of the emergency vehicles as it emits sufficient light even in the darkest of areas. Furthermore, since the heat produced by LED light bars is small, it won't adversely affect the interior of the vehicle.
LEDs are used in applications as diverse as aviation lighting, traffic signals and automotive lighting such as for brake lights, turn signals and indicators. LEDs have a compact size, fast switching speed and good reliability. LEDs are useful for displaying text and video and for communications. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players and other domestic appliances.
Solid state devices such as LEDs have excellent wear and tear if operated at low currents and at low temperatures. LED light output actually rises at colder temperatures (leveling off depending on type at around −30 C.). Consequently, LED technology may be a good replacement for supermarket freezer lights and will often last longer than other types of lighting.
Large-area LED signs and displays are used as stadium displays and as decorative displays. LED message displays are used at airports and railway stations, and as destination displays for trains, buses, trams, and ferries.
With the development of efficient high power LEDs, it has become more advantageous to use LED lighting and illumination. High power white light LED lighting is useful for illumination and for replacing incandescent and/or fluorescent lighting. LED street lights are used on posts, poles and in parking garages. LED's are now used in stores, homes, stage and theaters, and public places. Furthermore, color LED's are useful in medical and educational applications such as for mood enhancement. In many countries incandescent lighting for homes and offices is no longer available and building regulations require new premises to use LED lighting.
Conventional prior art LED lighting which is powerful enough for room lighting, however, is relatively expensive and require more precise current and heat management than fluorescent lamp sources of comparable output. Furthermore, conventional LED lighting can have a higher capital cost than other types of lighting and LED light tends to be directional with small areas of illumination. Moreover, conventional LED luminaries suffer from drawbacks due to a lack of lumen output and less than desirable light dispersion. Individually and combined, these aspects of conventional LED lighting can detract from efficient utilization of LED luminaries.
It is, therefore, desirable to provide an improved LED illuminating assembly, which overcomes most, if not all of the preceding problems and disadvantages.